In the past, soft contact lenses have required more-or-less daily maintenance by the user in order to clean the lenses and preserve both pliability and substantial sterility. The prior art porous lenses, usually fabricated from a suitable hydrophilic resin, have conventionally been immersed in a specifically formulated saline solution within a case or container particularly adapted for the purpose, the entire case being thereafter heated in a water bath to inactivate microorganisms. Overnight storage in the gradually cooling saline solution has allowed replacement of any fugitive moisture and has ensured continuance of the desired pliability of the lenses.
More recently, flexible versions of silicone resins have been adopted for the manufacture of soft contact lenses because a greater oxygen permeability. The latter property is important to contact lens users because the cornea does not have blood supply to deliver oxygen but rather relies on oxygen absorption directly from the atmosphere. Hence, oxygen permeable silicone lenses may be worn for longer periods of time without adverse health effects. However, the silicone resins employed for contact lenses have proved comparatively hydrophobic; and therefore, special permanent coatings have been developed to make certain that the soft silicone surface is readily wet for maximizing both adhesion to the eyeball about the corneal region and comfort to the patient.
Despite their advantages from the standpoint of improved user vision, coated silicone soft contact lenses are easily scratched; and the storage cases heretofore available have promoted undesirable scratching of these lenses by encouraging the user to remove each lens from the case by means of a wiping motion which causes consequent abrasive contact between the lens and its pocket or cavity in the case.